IB/ipath: ipath_skip_sge() can break if num_sge > 1

ipath_skip_sge() doesn't exactly duplicate the side effects of
ipath_copy_sge() if num_sge > 1 since it doesn't decrement ss->num_sge.
This could result in the sg_list being accessed out of bounds.
Since ipath_skip_sge() is almost always called with num_sge == 1,
the original "optimization" is almost never used.

Signed-off-by: Ralph Campbell <[e-mail]>
Signed-off-by: Roland Dreier <[e-mail]>

drivers/infiniband/hw/ipath/ipath_verbs.c

···
 {
 	struct ipath_sge *sge = &ss->sge;
 
-	while (length > sge->sge_length) {
-		length -= sge->sge_length;
-		ss->sge = *ss->sg_list++;
-	}
 	while (length) {
 		u32 len = sge->length;